The delivery of therapeutic agents to diseased muscle or other tissue is an important, often repeated, procedure in the practice of modem medicine. Therapeutic agents, including therapeutic drugs and genetic material, may be used to treat, regenerate, or otherwise affect the muscle surface or the interior of the muscle itself. Such therapy can promote revascularization and create new formation of muscle, such as the myocardium of the heart. For example, many of the treatments for congestive heart failure entail the delivery of therapeutic agents, growth factors, nucleic acids, gene transfection agents, or cellular transplants, e.g. fetal cardiomyocytes, allogeneic cardiomyocytes, allogeneic or autologous myocytes, and other potentially pluripotential cells from autologous or allogeneic bone marrow or stem cells.
Current methods for delivering therapeutic agents to muscle, such as the heart muscle, entail injecting directly into the muscle a genetic cell or therapeutic drug. Delivery of therapeutic agents has been proposed or achieved using medical devices such as catheters, needle devices and various coated implantable devices such as stents. The cells and agents can be injected directly or can be formulated into gels, sealants, or microparticles for injection.
Examples of methods for delivering drugs are shown, among others, in U.S. Pat. Nos. 6,224,566, to Loeb; 6,045,565, to Ellis et al.; 6,120,520, to Saadat et al.; and PCT Publication No. WO 00/54661, to Saadat.
Certain tissue, such as heart muscle tissue, present particular difficulties for effective implantation of therapeutic agents due to the nature of the tissue. For example, the beating of a heart and contraction of the heart muscle will move and generally expel material that is inserted or injected into the heart muscle on the next compression of the heart, or over time. Thus, it is difficult to keep the therapeutic agents in the injected location for treatment, and the overall efficacy of the therapy is reduced.
When therapeutic agents injected or delivered into the muscle are expelled due to the contractions of the muscle, other problems also arise. For example, therapeutic drugs may flow directly into the bloodstream, which is potentially harmful due to the toxic nature of some therapeutic drugs. Also, the costs involved in preparing therapeutic and genetic material are high. Accordingly, any loss of therapeutic agent during treatment represents a considerable financial loss.
Accordingly, there is a need for a system that stabilizes the therapeutic agent within the muscle.